The present invention relates to a method of producing an ink jet print head using a piezoelectric element as a driving source for ink exhaustion.
There has been a piezoelectric type ink jet print head using an piezoelectric element as a driving source for ink exhaustion. The print head generally includes a head base on which a plurality of separate ink paths are formed, a vibration plate fixed to the head base so as to cover all the separate ink paths, and piezoelectric elements adhering to portions of the vibration plate confronting the separate ink paths. An electric field is applied to the piezoelectric elements to deform the piezoelectric elements and further to deform the corresponding portions of the vibration plate, so that ink in the separate ink paths is pushed out of tip ports (nozzles) of the separate ink paths.
In order to mount piezoelectric elements in high density, there has been also presented a print head, for example, as shown in FIG. 10. In this print head, a plurality of (48 pieces in this example) separate ink paths 21 with a circular pattern extending from a group of nozzles at the center are formed on a head base 20, and a common ink path 22 for supplying ink to the separate ink paths 21 is formed around the separate ink paths 21. A vibration plate (not shown in FIG. 10) is fixed to the head base 20 so as to shut the separate ink paths 21 and the common ink path 22 tightly, and piezoelectric elements (not shown) each worked into a chip of a predetermined size are sticked to predetermined portions (shown by slanted lines) of the vibration plate one by one. Alignment marks 24 used at sticking the piezoelectric elements are provided at three positions on the head base 20.
However, in order to increase printing performance in the above described print head, it is required that the respective piezoelectric elements are precisely positioned to the predetermined portions of the vibration plate, that is, to the portions corresponding to the separate ink paths of the head base. However, in a case where piezoelectric elements are sticked one by one as in the above production method, it is difficult to make accurate positioning to the predetermined portions. If the sticked positions of the piezoelectric elements are off the predetermined portions, a pressure due to displacement of the piezoelectric element is not accurately applied to the corresponding portion of the vibration plate, so that printing becomes unstable and printing quality degrades.
Further, in the above production method., the piezoelectric elements are worked and sticked one by one, so that in case of the print head as shown in FIG. 10, there are required many mimes (48 times) of working and sticking of the piezoelectric elements. Thus, as the number of nozzles becomes large, a step from working to sticking becomes troublesome, a production time becomes long, and it becomes difficult to realize mass production. Especially, in order to improve printing performance, positioning precision of each piezoelectric element is important. However, in the case where piezoelectric elements are sticked one by one, high repetition precision for the number of the piezoelectric elements are required, which becomes a great barrier for mass production.